Delete statement in SQL is very slow

Question

I have statements like this that are timing out:

DELETE FROM [table] WHERE [COL] IN ( \'1\', \'2\', \'6\', \'12\', \'24\', \'7\', \'3\', \'5\')

Answer 1

Preventive Action

Check with the help of SQL Profiler for the root cause of this issue. There may be Triggers causing the delay in Execution. It can be anything. Don't forget to Select the Database Name and Object Name while Starting the Trace to exclude scanning unnecessary queries...

Database Name Filtering

Table/Stored Procedure/Trigger Name Filtering

Corrective Action

As you said your table contains 260,000 records...and IN Predicate contains six values. Now, each record is being search 260,000 times for each value in IN Predicate. Instead it should be the Inner Join like below...

Delete K From YourTable1 K
Inner Join YourTable2 T on T.id = K.id

Insert the IN Predicate values into a Temporary Table or Local Variable